Check Your Vitamin D Level Before Taking Supplements

Copyright Robert P. Heaney, 2011. Used with permission.

This chart is interesting! It shows that the effectiveness of vitamin D supplements in terms of actual rise in blood level of vitamin D depends on the starting level. For example, if your starting level is at 20 ng/mL, taking a 1000 IU per day supplement can raise your blood level by about 10 ng/mL. But the same 1000 IU per day increase your blood level by only 4 ng/mL if you are already at 60 ng/mL. And it practically does nothing if you are at 80 ng/mL.

This knowledge can help consumers and doctors decide an appropriate level of vitamin D supplementation.

Many people take vitamin D supplements, either on their own, or because they have been prescribed to them by their doctors. The media is full of news about vitamin D deficiency and a common response is to take a daily vitamin supplement. But does it work?

According to this chart, the answer is it depends! If you are in the 40 -60 ng/mL range, which most experts believe to be ideal, popping a pill because of the media frenzy about vitamin D deficiency is completely useless. You are better off watching your diet and lifestyle by consuming vitamin D rich foods (dairy, fortified juices, fatty fish and mushrooms) and getting limited sun exposure without sun screen. Your body creates a reserve of vitamin D in your fat cells, which can help you go through the winter months when you are not able to get much sun. The vitamin D calculator can help you estimate your vitamin D intake from food and sun exposure.

If you are clinically diagnosed as having insufficient or deficient levels of vitamin D, you should look at your baseline blood level of vitamin D and talk to your doctor about an appropriate amount of supplementation. Use the above chart as a starting point of discussion. Do not blindly accept a high dose of vitamin D supplement because it can cause toxicity. Your doctor will use a try-and-wait approach, but you need to ask questions and convince yourself that the prescribed treatment makes sense for you.